The quinones are a large and varied group of natural products found in all major groups of organisms. Quinones are a group of aromatic dioxo compounds derived from benzene or multiple-ring hydrocarbons such as naphthalene, anthracene, etc. They are classified as benzoquinones, naphthoquinones, anthraquinones, etc., on the basis of the ring system. Quinones have a variety of medicinal and industrial uses. Many efficient antineoplastic drugs are either quinones (anthracycline derivatives, mitoxantrone, actinomycin), quinonoid derivatives (quinolones, genistein, bactracyclin), or drugs such as etoposide that can easily be converted to quinones by in vivo oxidation. Gantchev et al. (1997) Biochem. Biophys. Res. Comm. 237:24-27. Quinones are now widely used as anticancer, antibacterial and anti-malarial drugs, as well as fungicides. The antitumor activities of the quinones were revealed more than two decades ago when the National Cancer Institute published a report in which fifteen-hundred synthetic and natural quinones were screened for their anticancer activities. Driscoll et al. (1974) Cancer Chemot. Reports 4:1-362.
More particularly, β-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione), a quinone, is derived from lapachol (a naphthoquinone) which can be isolated from the lapacho tree (Tabebuia avellanedae), a member of the catalpa family (Bignoniaceae). Lapachol and β-lapachone (with numbering) have the following chemical structures:

β-lapachone, as well as its intermediates, derivatives and analogs thereof, are described in Li, C. J. et al., (1993) J. Biol. Chem., 268(30): 22463-22468.
As a single agent, β-lapachone has demonstrated significant antineoplastic activity against human cancer cell lines at concentrations typically in the range of 1-10 μM (IC50). Cytotoxicity has been demonstrated in transformed cell lines derived from patients with promyelocytic leukemia (Planchon et al., (1996) Cancer Res., 55: 3706-3711), prostate (Li, C. J., et al., (1995) Cancer Res., 55: 3712-3715), malignant glioma (Weller, M. et al., (1997) Int. J. Cancer, 73: 707-714), hepatoma (Lai, C. C., et al., (1998) Histol Histopathol, 13: 89-97), colon (Huang, L., et al., (1999) Mol Med, 5: 711-720), breast (Wuertzberger, S. M., et al., (1998) Cancer Res., 58: 1876), ovarian (Li, C. J. et al., (1999) Proc. Natl. Acad. Sci. USA, 96(23): 13369-13374), pancreatic (Li, Y., et al., (2000) Mol Med, 6: 1008-1015; Li, Y., (1999) Mol Med, 5: 232-239), and multiple myeloma cell lines, including drug-resistant lines (Li, Y., (2000) Mol Med, 6: 1008-1015). No cytotoxic effects were observed on normal fresh or proliferating human PBMC (Li, Y., (2000) Mol Med, 6: 1008-1015).
β-lapachone appears to work by inducing unscheduled expression of checkpoint molecules, e.g., E2F, independent of DNA damage and cell cycle stages. Several studies have shown that β-lapachone activates checkpoints and induces apoptosis in cancer cells from a variety of tissues without affecting normal cells from these tissues (U.S. Patent Application Publication No. 2002/0169135, incorporated by reference herein). In normal cells with their intact regulatory mechanisms, such an imposed expression of a checkpoint molecule results in a transient expression pattern and causes little consequence. In contrast, cancer and pre-cancer cells have defective mechanisms, which result in unchecked and persistent expression of unscheduled checkpoint molecules, e.g., E2F, leading to selective cell death in cancer and pre-cancer cells.
β-lapachone has been shown to be a DNA repair inhibitor that sensitizes cells to DNA-damaging agents including radiation (Boothman, D. A. et al., Cancer Res, 47 (1987) 5361; Boorstein, R. J., et al., Biochem. Biophys. Commun., 117 (1983) 30). β-lapachone has also shown potent in vitro inhibition of human DNA Topoisomerases I (Li, C. J. et al., J. Biol. Chem., 268 (1993) 22463) and II (Frydman, B. et al., Cancer Res., 57 (1997) 620) with novel mechanisms of action. Unlike topoisomerase “poisons” (e.g., camptothecin, etoposide, doxorubicin) which stabilize the covalent topoisomerase-DNA complex and induce topoisomerase-mediated DNA cleavage, β-lapachone interacts directly with the enzyme to inhibit catalysis and block the formation of cleavable complex (Li, C. J. et al., J. Biol. Chem., 268 (1993) 22463) or with the complex itself, causing religation of DNA breaks and dissociation of the enzyme from DNA (Krishnan, P. et al., Biochem Pharm, 60 (2000) 1367). β-lapachone and its derivatives have also been synthesized and tested as anti-viral and anti-parasitic agents (Goncalves, A. M., et al., Mol. Biochem. Parasitology, 1 (1980) 167-176; Schaffner-Sabba, K., et al., J. Med. Chem., 27 (1984) 990-994).
More specifically, β-lapachone appears to work by disrupting DNA replication, causing cell-cycle delays in G1 and/or S phase, inducing either apoptotic or necrotic cell death in a wide variety of human carcinoma cell lines without DNA damage and independent of p53 status (Li, Y. Z. et al. (1999); Huang, L. et al.). Topoisomerase I is an enzyme that unwinds the DNA that makes up the chromosomes. The chromosomes must be unwound in order for the cell to use the genetic information to synthesize proteins; β-lapachone keeps the chromosomes wound tight, so that the cell cannot make proteins. As a result, the cell stops growing. Because cancer cells are constantly replicating and circumvent many mechanisms that restrict replication in normal cells, they are more vulnerable to topoisomerase inhibition than are normal cells.
Another possible intracellular target for β-lapachone in tumor cells is the enzyme NAP(P)H:quinone oxidoreductase (NQO1). Biochemical studies suggest that reduction of β-lapachone by NQO1 leads to a “futile cycling” between the quinone and hydroquinone forms with a concomitant loss of reduced NADH or NAD(P)H (Pink, J. J. et al., J. Biol. Chem., 275 (2000) 5416). The exhaustion of these reduced enzyme cofactors may be a critical factor for the activation of the apoptotic pathway after β-lapachone treatment.
As a result of these findings, β-lapachone is actively being developed for the treatment of cancer and tumors. In WO 00/61142, for example, there is disclosed a method and composition for the treatment of cancer, which comprises the administration of an effective amount of a first compound, a G1 or S phase drug, such as a β-lapachone, in combination with a G2/M drug, such as a taxane derivative. Additionally, U.S. Pat. No. 6,245,807 discloses the use of β-lapachone, amongst other β-lapachone derivatives, for use in the treatment of human prostate disease.
In addition to β-lapachone, a number of β-lapachone analogs having anti-proliferative properties have been disclosed in the art, such as those described in PCT International Application PCT/US93/07878 (WO 94/04145), which is incorporated by reference herein, and U.S. Pat. No. 6,245,807, incorporated by reference herein, in which a variety of substituents may be attached at positions 3- and 4- on the β-lapachone compound. PCT International Application PCT/US00/10169 (WO 00/61142), incorporated by reference herein, discloses β-lapachone, which may have a variety of substituents at the 3-position as well as in place of the methyl groups attached at the 2-position. U.S. Pat. Nos. 5,763,625, 5,824,700, and 5,969,163, each of which is incorporated by reference herein, disclose analogs with a variety of substituents at the 2-, 3- and 4-positions. Furthermore, a number of journals report β-lapachone analogs with substituents at one or more of the following positions: 2-, 3-, 8- and/or 9-positions, (See, Sabba et al., (1984) J Med Chem 27:990-994 (substituents at the 2-, 8- and 9-positions); (Portela and Stoppani, (1996) Biochem Pharm 51:275-283 (substituents at the 2- and 9-positions); Goncalves et al., (1998) Molecular and Biochemical Parasitology 1:167-176 (substituents at the 2- and 3-positions)).
Moreover, structures having sulfur-containing hetero-rings in the “α” and “β” positions of lapachone have been reported (Kurokawa S, (1970) Bulletin of The Chemical Society of Japan 43:1454-1459; Tapia, R A et al., (2000) Heterocycles 53(3):585-598; Tapia, R A et al., (1997) Tetrahedron Letters 38(1):153-154; Chuang, C P et al., (1996) Heterocycles 40(10):2215-2221; Suginome H et al., (1993) Journal of the Chemical Society, Chemical Communications 9:807-809; Tonholo J et al., (1988) Journal of the Brazilian Chemical Society 9(2):163-169; and Krapcho A P et al., (1990) Journal of Medicinal Chemistry 33(9):2651-2655). More particularly, hetero β-lapachone analogs are disclosed in PCT International Application PCT/US03/037219 (WO 04/045557), incorporated by reference herein.
Quinones also have a number of other medicinal uses. Terpenoid-type quinones are also useful as treatments for diabetes. U.S. Pat. No. 5,674,900. Additional quinones can be used to treat cirrhosis and other liver disorders. U.S. Pat. Nos. 5,210,239 and 5,385,942.
Hydroquinone amines and quinone amines are also useful for treating a number of conditions, including spinal trauma and head injury. U.S. Pat. No. 5,120,843. Degenerative central nervous system diseases, as well as vascular diseases, are treatable with quinones such as Idebenone [2,3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1,4-benzoquinone] and Rifamycin. S. Mordente et al. (1998) Chem. Res. Toxicol. 11:54-63; Rao et al. (1997) Free Radic. Biol. Med 22:439-46; Cortelli et al. (1997) J. Neurol. Sci. 148:25-31; and Mahadik et al. (1996) Prostaglandins Leukot. Essent. Fatty Acids 55:45-54. A vitamin K analog, 6-cyclo-octylamino-5,8-quinoline quinone shows efficacy for treatment of leprosy and tuberculosis. U.S. Pat. No. 4,963,565. Hydroquinone is also used to treat skin pigmentation disorders. Clarys et al. (1998) J. Dermatol. 25:412-4. Mitomycin C-related drug indoloquinone EO9 has demonstrated cell killing against HL-60 human leukemia cells, H661 human lung cancer cells, rat Walker tumor cells and human HT29 colon carcinoma cells. Begleiter et al. (1997) Oncol. Res. 9:371-82; and Bailey et al. (1997) Br. J. Cancer 76:1596-603.
Quinones such as aloin, a C-glycoside derivative of anthraquinone, accelerate ethanol oxidation and may be useful in treating acute alcohol intoxication. Chung et al. (1996) Biochem. Pharmacol. 52:1461-8 and Nanji et al. (1996) Toxicol. Appl. Pharmacol. 140:101-7. Quinones capsaicin and resiniferatoxin blocked activation of nuclear transcription factor NF-κB, which is required for viral replication, immune regulation and induction of various inflammatory and growth-regulatory genes. Singh et al. (1996) J. Immunol. 157:4412-20. Antiretroviral and antiprotozoan naphthoquinones are described in U.S. Pat. Nos. 5,780,514 and 5,783,598. Anthraquinones are also useful as laxatives. Ashraf et al. (1994) Aliment. Pharmacol. Ther. 8:329-36; and Muller-Lissner (1993) Pharmacol. 47 (Suppl. 1): 138-45.
Because of the wide variety of biological processes in which quinones play a critical role, it would be advantageous to develop novel quinones for various uses, including disease treatment.
One obstacle, however, to the development of pharmaceutical formulations comprising quinones, such as β-lapachone or β-lapachone analogs for pharmaceutical use is the low solubility of many quinone compounds, including β-lapachone compounds, in pharmaceutically acceptable solvents. There are also drawbacks related to the pharmacokinetic profiles of traditional formulations comprising quinones. As a result, there is a need for improved formulations of quinone compounds for pharmaceutical administration, which are both safe and readily bioavailable to the subject to which the formulation is administered.